Air pollution study must factor in bushfire smoke

“However, for Perth, where smoke sources are diffuse, the prospect of developing an accurate forecasting tool is low compared to Sydney and Melbourne where large bushfires are more common and close to the cities.”—Mr Price. Image: Steve MarrA STUDY of Perth’s air quality by interstate universities to help predict future pollution levels has determined the accuracy of forecast models for the region would be low due to diffuse sources of bushfire smoke.

Researchers from the Universities of Wollongong and Tasmania investigated the relationship between daily pollution levels and the daily spatial pattern of hotspot (fire) activity in the landscapes surrounding Perth and Sydney.

The researchers used daily thermal anomalies detected by the orbital MODIS system as well as pollution concentrations and meteorological data from 2002 to 2008.

They then examined the statistical relationship between fire activity in the landscape and pollution levels around the two cities, which were chosen out of 20 prospective locations nationwide for their best run of pollution data.

University of Wollongong Centre for Environmental Risk Management of Bushfires senior research fellow Owen Price says the study built on previous research which highlighted the relationship between bushfire smoke and human health impacts.

Mr Price says there is a definite connection between fire activity and pollution in urban centres but that there are separate windows of influence of fire activity on pollution.

“The main source of bushfire smoke in Sydney is within 100 km of the city, whereas for Perth the source is more diffuse or up to 400 km away,” he says.

“Smoke levels were higher when the atmosphere was more stable and when the wind was blowing on-shore.

“This is the opposite weather to that which promotes fire activity and bushfire smoke transport to the city, which suggests that most pollution is caused by sources other than smoke.”

Mr Price says they now hope to improve the predictive ability of the method by using atmospheric transport models that can track the likely path of smoke from each fire.

“However, for Perth, where smoke sources are diffuse, the prospect of developing an accurate forecasting tool is low compared to Sydney and Melbourne where large bushfires are more common and close to the cities.”

Edith Cowan University Centre for Ecosystem Management Associate Professor Andrea Hinwood says the interstate team’s theory of modelling where the pollution is going to go is a tool that has been used in many jurisdictions and in the USA.

“Traditionally we have looked at air pollutants in Perth and hospitalisation in Perth associated with air pollution, what we haven’t done is look at the contribution of bushfire smoke,” she says.

“Our focus has been on peat smoke so we can certainly say that most of the components of bushfire smoke and peat smoke have been associated with health effects in other studies.

“Whether that actually translates to a (negative) health effect in the population is very hard to discern.”